Altruism works when a person takes their own interests as equal with that of others.
The method upon which altruism is delivered is where people adhere to the neo-utilitarian imperative through maximising the net positive aspects of sentience in the cosmos (happiness, ecstasy, positive meaning, wellbeing, health etc.) whilst minimising the net negative aspect of sentience (suffering) in the cosmos.
This is adherence is combined with a view to elicit an equal share of the positive and negative aspects of sentience across all social agents.
This is the bedrock of altruistic ethics.
Henry Willoughby's Social Justice Blog 